Off-line feedback path modeling circuitry and method for off-line feedback path modeling

Abstract

An off-line modeling system ( 50 ) is provided for modeling a feedback path by calculating filter taps. The off-line modeling system ( 50 ) includes a reference sensor ( 16 ), a secondary source ( 18 ), and an off-line modeling circuitry ( 10 ). The reference sensor ( 16 ) receives a noise signal and a feedback signal ( 22 ) and generates a primary signal x(n) in response. The secondary source ( 18 ) receives a modeling signal v(n) and provides the modeling signal v(n) to the feedback path. The off-line modeling circuitry ( 10 ) includes a signal discrimination circuitry ( 54 ), a modeling signal generator ( 64 ), a feedback path modeling adaptive filter ( 60 ), and associated adaptive algorithm ( 62 ) and a summing junction ( 58 ). The signal discrimination circuitry ( 54 ) receives the primary signal x(n) and generates a modified modeling signal v′(n). The modeling signal generator ( 64 ) generates the modeling signal v(n). The feedback path modeling adaptive filter ( 60 ) receives the modeling signal v(n) and uses adaptive algorithm ( 62 ) to process the modeling signal v(n). In doing this, adaptive algorithm ( 62 ) calculates the filter taps. The summing junction ( 58 ) subtracts the output signal from the modified modeling signal v′(n) to generate the modeling error signal which is used by the adaptive algorithm ( 62 ).

What is claimed is:  
     
       1. An off-line modeling system for modeling a feedback path by calculating filter taps, the off-line modeling system comprising: 
       a reference sensor operable to receive a noise signal and a feedback signal and to generate a primary signal in response;  
       a secondary source operable to receive a modeling signal and to provide the modeling signal to the feedback path; and  
       an off-line modeling circuitry for modeling the feedback path including:  
       a signal discrimination circuitry operable to receive the primary signal and to generate a modified modeling signal, said signal discrimination circuitry including:  
       a decorrelation delay unit operable to delay the primary signal and to generate an output signal that corresponds to a delayed primary signal,  
       an adaptive discrimination filter operable to receive the output signal and the modified modeling signal and to filter the output signal to generate a predicted noise signal, and  
       a second summing junction operable to subtract the predicted noise signal from the primary signal to generate the modified modeling signal,  
       a modeling signal generator operable to generate the modeling signal,  
       a feedback path modeling adaptive filter operable to receive the modeling signal and a modeling error signal and to filter the modeling signal to generate an output signal and to calculate the filter taps, and  
       a summing junction operable to subtract the output signal from the modified modeling signal to generate the modeling error signal which is provided to an adaptive algorithm used by the feedback path modeling adaptive filter.  
     
     
       2. An off-line modeling circuitry for modeling the feedback path of an active noise control system, the off-line modeling circuitry comprising: 
       a signal discrimination circuitry operable to receive a primary signal and to generate a modified modeling signal, said signal discrimination circuitry including:  
       a decorrelation delay unit operable to delay the primary signal and to generate an output signal that corresponds to a delayed primary signal,  
       an adaptive discrimination filter operable to receive the output signal and the modified modeling signal and to filter the output signal to generate a predicted noise signal, and  
       a second summing junction operable to subtract the predicted noise signal from the primary signal to generate the modified modeling signal;  
       a modeling signal generator operable to generate a modeling signal;  
       a feedback path modeling adaptive filter operable to receive the modeling signal and a modeling error signal and to filter the modeling signal to generate an output signal and to generate filter taps; and  
       a summing junction operable to subtract the output signal from the modified modeling signal to generate the modeling error signal which is provided to an adaptive algorithm used by the feedback path modeling adaptive filter.  
     
     
       3. The off-line modeling circuitry of claim  2 , wherein the delay of the decorrelation delay unit is a programmable delay. 
     
     
       4. The off-line modeling circuitry of claim  2 , wherein the delay is equal to or greater than the delay of the feedback path being modeled. 
     
     
       5. A method for off-line feedback path modeling comprising the steps of: 
       generating a modeling signal and providing to an environment;  
       receiving a primary signal from the environment;  
       generating a modified modeling signal using the primary signal and a digital delay that is equal to or greater than the delay of the feedback path being modeled; and  
       generating filter taps for use in a feedback neutralization filter by adaptively filtering the modeling signal using an adaptive filter and the modified modeling signal.